Different filters are used in photography and cinematography for photographing or filming in specific lighting conditions. Protective and UV filters, polarising filters, filters correcting colour balance, filters absorbing a particular colour, contrast enhancing filters, infrared filters, neutral grey filters and filters required to achieve various effects can be distinguished. Filters are either round or square. Round filters consist of the filter itself and a filter collar that is threaded for attachment to front of the lens. A filter suited for this particular diameter has to be obtained for each lens diameter. Square filters consist of a filter holder and the filter itself. Every lens diameter requires a filter holder suited for this particular diameter but filters itself can be purchased in one size independent of the lens diameter.
Sometimes two or more filters have to be used simultaneously. Filter package holders containing two or more filter holders stacked together and comprising a pair of parallel slots pointed towards each other, whereas one round filter can be installed in each pair of slots, are known (e.g. GB2097546, Attachment of filters to a camera lens). The filters can be slid forwards and backwards in the slot, which is particularly useful when using filters with properties varying between the edges, e.g. filters of variable darkness or colour. In addition to using several filters at the same time rotating of filters is also necessary. Only round filters can be rotated in case of the known solution; the solution does not enable rotation and usage of square filters.
Additionally, using suitable sunshades is also required to prevent the lens from being exposed to direct sunlight. Usually at least an upper sunshade and one or two lateral sunshades have to be used, whereas the position of the lateral sunshades has to be extremely adjustable first of all, to prevent the lateral sunshades from getting in the frame, primarily in case of wide-angle shots. Adjusting the position of the lateral sunshades and the upper sunshade has to be simple and convenient. Maintaining the position of the lateral sunshades and upper sunshade in relation to light sources or the workplane has to be possible when rotating the filters and/or camera.
Also known is WO03/058316, disclosing an optical filters quick assembly support system for a motion picture or professional video cameras, comprising a mount base ring, one or more filter holders, rotatable relative to the mount base ring, and a sunshade. While this solution allows to use multiple filters and rotate such filters relative to each other, the sunshade cannot be rotated relative to the mount base, and the mount base cannot be rotated relative to the objective as the mount base is fixed to the camera body.
Thus, a device enabling rotation of square filters in relation to the lens, enabling rotating the sunshades in relation to the lens, and enabling to rotate square filters relative to the sunshades is required. Such device should be preferably equipped with an upper sunshade and lateral sunshades that are easily adjustable to adequate extent, including using for taking wide-angle shots; easily attached to and detached from the camera, and with filters located as close to the lens as possible.